Automatic control of inspirators for gas plants



D. W. SHAEFFER AUTOMATIC CONTROL OF INSPIRATORS FOR GAS PLANTS FiledNov. 5, 1947 m m" M W 5 V H U m N R D MA .A Y B mm m0 lb A oo wm Nb mmo-.

Patented Aug. 26, 1952 AUTOMATIC CONTROL OF INSPIRATORS- FOR GAS PLANTS-David W. Shaefier, St. Louis, Mo., assignor to Phillips PetroleumCompany, a corporation of Delaware Application November 3, 1947, SerialNo. 783,661 (01. 48180) 4 Claims.

This invention relates to gas air inspirator systems. In one of its morespecific aspects it relates to an electrically operated and fullyautomatic gas air inspirator system.

One object of my invention is to provide an electrically operated andfully automatic gas air inspirator system. Another object of myinvention is to provide an electrically operated and. fully automaticgas air inspirator system which continues tofunction even during periodsof electric power failure. Still another object of my invention is toprovide an electrically operated inspirator system, which during timesof electric power failure, continues in smooth and uninterruptedoperation.

Electrically operated inspirator systems are relatively simple toconstruct and operate and the operation of such systems is very easy tocontrol. However, in case of electric storm when the electric power isinterrupted or when power is cut off for any reason whatever, suchinspirator systems as now in operation cease to function. I have devisedan inspirator system which, as mentioned hereinbefore, is adapted tocontinue operation even during periods of electric power failure.

The figure illustrates diagrammatically one form of apparatus in whichto carry out the improved method of my invention. Referring to *thefigure; reference numeral Iwrefers to the gas or liquified gas storagetank which contains gas to be inspirated. Gas from the storage tank Ipasses by way of a pipe la, a valve 3 and a pipe 2 to a pressurereducing valve 4. From this valve the gas continues passage through line2, a valve 5, .a line B, a line 9 and a valve In to a second pressurereducing valve I. From this valvethe gas continuespassage on through aline 9, a valve 12, some pipes i6 and 3|", a pipe 28, some valves 29,2'1 and. From 'pipe 28 the gas passes then through a pipe 34 into amanifold 35 which distributes the gas through some individual lead pipes34a, 31, 39 and 4| through some valves 36,

38, 4D: and 42,-=resp.ectively, into severalcunits of V the insp'irato'rZsyste'm: Reference numerals 43, :44; 45" andf46" refer. to somesolenoid: operated on-off. valves. From; thesesolenoid.;operated valvesgas p'assesinto-the respective inspirators 41,48, 49 :andf50. Fromrtheseinspirators the gas air mixture'or mixtures pass through some ducted tomy inspirator system through wires, and a. These wires connect with apressure operated multiple controller switch unit ,65. From this unit65, some lead wires 60, 62 and 64 are connected directly with thesolenoid valves 45, 44 and 43 respectively. Some return wires 59, El and63 from these three solenoids are connected to a common return wire 68which in turn is connected'with one side 66a of the power line. To thisreturn wire 68 is also connected a return wire 51 from the solenoidvalve 45. The other wire 53 from this solenoid valve 46 is directlyconnected to the source of power wire 56. The wire 5'! passes throughone portion of a signal assembly H and through the electrical switchportion of a pressure operated electrical switch 69. From this pressureoperated switch, a pipe it leads to the gas main 56.'

Also from the pressure operated multiple controller switch 65 a pipe 61leads to the gas main 56. Pipe 1 and valve 6 serve as a bypass: aroundthe pressure reducing valve 4, and pipe I4 and valve 13 serve a similarpurpose around the pressure reducing valve II. In a like manner, pipe 32and valve 33 form a bypass around the valve 21. From pipe 3| a pipe I!leads to a pressure reducing valve I8, the downstream side of which isconnected to a pipe 19 which carries a restricting orifice 20. On thedownstream side of the orifice 20 a pipe 24 leads to the underside ofthe motor 26 of a motor regulator valveassembly 25. This assemblyconsists of the motor 25, a valve 21, which are connected by a valvestem 2 I.

To the downstream end of pipe I9 is connected a valve 23 which is abackpressure regulator type of valve. From this valve pipe 22 leads to thegas main 56.

The pressure reducing valves 4, II and [8 are of the constant pressureoutlet type of valve, and in operation valve 4 is intended to reduce thegas from its storage tank pressure to about 50 pounds per square inchValve H is intended toreduce the pressure from this 50 pounds to about.25 pounds while the valve la is intended to reduce the pressure from 25pounds to that of an 18inch column of water. i Lowpressures in. suchsystems, that-is, .pressures of a few ouncesper square inch arefrequently measured and expressed in terms of inches of a column ofwater, for example, the 18 inch water column pressure above mentionedmeans the pressure exerted by a oolumnof water 18 inches high; if i iThe motor re'g ulator valve assembly 251 is of the zero governorthrottle type and isvintendedto 3 throttle the flow of gas through valve21 or to shut olf entirely valve 2? in response to gas pres sure in pipe24.

The solenoid operated on-off valves 43, 44 and 45 are of a type thatwhen electric current is flowing through the solenoids, the valves areheld fully open, and conversely when the electric current is not flowingthrough these solenoids, the valves automatically close. The solenoidoperated on-off valve 45 is like the other solenoid valves excepting itoperates in exactly the reverse manner, when the electric current isflowing through wires 5'! and 53 the solenoid holds valve 46 closed andwhen electricity .ceases to. flow through wires 51 and 53 from anycausewhat-- ever, the valve 46 opens.

The pressure operated multiple controllerswitch 65 is standard equipmentand may be purchased from instrument supply houses. This pressure switch65 operates in response to gas pressure in the main 55 and. as pressurein the main 56 decreases; the valve 43 opens, when pressure in 50:decreases'further the, valve 44- also opens andsimilarly uponra stillfurther decrease in main pressure the third valve 45 opens.

1a the. operation of my apparatus, the valves 5; l3 and are normallyclosed so that gas to be inspir ated" will. he forced to pass throughthe 1 'ul'ators 4,. H and valve 2:! and accordingly high: pressure gassuchaspropane from the storagetankwill flow through: line [a at tankpres- Su'r'eto the regulator valve 4. Thisvalve reduces the pressureonzthn propane to. a 50 pound discharge pressure. This 50 pound propanethen continues. through line 2,.line. 8, line 9 to valve II. On passingthrough; this valve. the pressure on the; propane is reducedzto aconstant outlet'value of about pounds. per. square inch. This 25 pound.propane; then. flows on through. line 9, valve I 2 through. pipes 31 and28. In normal operation, the motor va ve. 21. is fully open and thepropane of 25 pounds pressure or approximately at that: pressurepassesion through valve and line. 34; to the manifold 35-. From themanifold 35' the. propane passes through the in- .spirators 41,. 48 and49 depending uponthe gas requirements of the system. In one casein whichaisystemwasdesigned for a maximum demand of 20001 cubic feet per houroutput, the inspirator 4:1 was: of: such: size: as to have a capacity of500 cubic; feet per hour, inspirator had a capacity of 1500 cubic feetper'houninspirator 49 had a capacity-'of2000' cubic-feet per hour. Thestandby; inspirator 50'had a capacity of 3000 cubic feet pershouri.Thuswith. a normal maximum demand M12000 cubic feet. per hour,inspirators 41 and 48 could carry the load. When demand exceeded 2000cubic. feet. per hour, then inspirator 49 would turn-chin responset'oapredetermined drop. in gas main: pressure. With this inspirator 49operationthe': total outputof the three-inspiratorswas 40.00: cubicfeet. per hour and this large output would soon raise. the pressure inthe gas main to such arr extentthat the controller switch 65 wouldoperate-triclose the solenoid operated valve 45. In like manner, whenthe valves 43 and 44 were open permitting the production of about-2000icubi"c*feet; of gas per hour and if the load 65 to close off thevalve 44 for such a length o'itime until the gasxmain pressure droppedsufrficientlytoopenthe valve 44 again.

times while electric current is available.

' propane from.manifold line 35 through pipe 4|,

through valve 42-; valve 46 and through the inspirator-50. Thisinspirator 50 may be of a 3000 cubic feet per hour capacity so that itcan more than satisfy the normal maximum demand on the system. Dischargefrom the inspirator 50 flows through-ivalve; 54-, the manifold line. 55into the gas: main 5.6; Since the valve 45 is of, the fully opened orfully closed type, when it is open pressure in the gas-mainusually'builds up quite rapidly if the demand onthe system is less than3000. cubic feet. per hour. I have devised athrottling' control for useunder such condition so that .the pressure in thegas mainwill notcontinue-to increase to such an extent as to rupture pipes or'otherwisecreate hazards. The throttling action mentioned is accomplished by theoperation of. the zero governor-valve assembly 215. In normalplantoperation if. thev gas. pressure in the main 56 is intended to. be.a maximum of about 6 inches of water column (W. C.) when the pressure.in the. main exceeds; 6 inches, water'column very. slightly. the, backpressure regulator valve 23 operat'esrto. close part-1y. This; partialclosing of.valve .23. causesthe pressure, on the downstream side; oforifice 20 in line IE: to increase somewhat and this increase. of"pressure is; transmitted through pipe: 24 to the underside ofv thediaphragm in themotor-ZG and this increase ofpressure on the diaphragmoperates tov close partly or throttle. the: valve. '21 In this mannerthe propane reaching the valve 21: leaves this valve at a pressure lessthan: 25 pounds per. square inch. And. at. a pressure lower; than 25pound per square inch less propane. flows through manifold line 35' andthrough. the. solenoid valve 46 and inspirator. 50. and accordinglypressure in :the gas main. 56' drops. These several apparatus par-ts,that is, control valve 23, the zero governor 25, cooperativelyoperateito maintain a desired max.- imum gas. main. pressure of about 6inches W. C. If for some. reason. pressure. inthe gas main decreasesbelow 6 inchesW. C; valve 23'opens some- V spirator, the regulator valve25 and the pressure regulator valve- 23 are so adjusted that the valve2T will be. throt'tled tosuch an extent-"thatit will passapropanea atabout. l0 pounds per square inch pressure. At this pressure theinspirator 5 0 will add sufiicientair that the mixture discharging fromthis inspirator will. have a. B. t; u. content of approximately 8.00 percubic 'foot'.-Of course, the inspirator 50 canjbe set to discharge: thegas air mixture at any desired-B. :t. urcontentn When the threeinspirators 4.1, 48q-and 4,9 are operating under 2.5 pounds pressuretqgproduce'approxi mately 800 B. u. gas air mixtures, the inspiratorillsh" uld be so adjusted as to proddceagas air mix ur'efof the-sameh'eating' value-so that standpaperless-win be the same as 'normal'opera- At'ti'meswhen the demand on; such' a system i's exceedin lygreat, I'have made provisionthat inspirator Silmay be opened to thesystem to help satisfy "the demand. The apparatus which permitssimultaneous use of a large inspirator 59 is aypressure operatedelectrical switch 69'.- The pres'sureportionpf this switch is connectedby pipe 'to "the gas main 56. In operationwhen the inspirators 41, 48and 49 are making gas and the-pressure in the gas main decreases to alow value as forexample, 4 to 5 inches W. C. this low pressure istransmitted throughpipe 10 to the ressure operated switch 69whichcausesthe switchtd dp'en'and break the electrical circuit flowingthrough-Wires Hand 58. When this circuit i'sbroken-the solenoid valve 46snaps open and-propane at pounds pressure then flows through inspiratorand into the gas main 56. Under such conditions pressure in the gasmainsoon increases to such an extent that the pressure'operated electricswitch 69 operates to close the circuit in wires 51 and 58 and close thesolenoid operated valve 46. I

I As mentionedabove, the inspirator 59, in one installation, wasadjusted to produce an 800 Bxt. u. gas airmixture at apropane pressureof 10 pounds persquare inch and under this adjustment. when propaneflows through this inspirator at 25 pounds per square' inchproportionately more air isdrawn into the gas and the gas air mixtureemerging has a lower B. t. u. content. In

one case, atapropane pressure of 25pounds per square-inch, I found thatthe B. t. u. content of the gas air mixture was 750 per cubic foot.While this B. t. ,u. contentmay be abnormally low, yet it will have onlya small effect on the B. t. u. content of the gas air mixturein the main56, since that issuing from inspirator 59 will be mixed with themixtures issuing from the other three inspirators. v l I The samecondition will exist at times of power failure when the standbyinspirator 50 snaps into operation to-replace the inspirators 41,48"an'd 49. Atthe instant of change when inspirators 41,48 and 49 closeand inspirator 50 opens, propane will reach the latter inspirator at 25pounds per square inch. This high pressure will cause the pressure inthe gas main to increase rather quickly above 6 inches of W. C. and thisincrease in gas main pressure will be transmitted to the regulator valve23, cause pressure in pipes I9 and 24 to increase and this increaseaccordingly operates the motor 26 to throttle the valve 21. This lastoperation takes place quite rapidly so that the large volume of propaneat 25 pounds pressure passes through the inspirator 50 for only a veryshort time and accordingly the low B. t. u. gas air mixture frominspirator 5D is discharged and enters the main 56 only momentarily orfor such a period of time until the motor valve .25 throttles to reducethe propane pressure reaching the inspirator 5B. As soon as this propanepressure is cut to 10 pounds per square inch then the normal gas airmixture of 800 B. t. u. will be produced in the inspirator 50.

I have found that the switching from the inspirators 41, 48 and 49 tothe standby inspirator 50 is so rapid and noiseless that an operatorseldom knows that the change has been made. Of course, the change ismade on account of the power failure,'and when a power failure occursthe operator should be warned in some manner;

To furnish a warning under such conditional have shown in the drawing asignal assembly" which isintended to turn on a light or ring' a hell orotherwise warn the operatorthat theelectrlc power has failed and thatthe standby inspirator 50 is in operation. In case the signal assemblyincludes an electric light bulb or a bell, a battery should be providedto furnish electricity for this signal. The operation of this assemblyis very simple and is such that when the current. fails to flow in wires51 and 58 for any reason whatever, a relay Ila. operates to cause thebattery circuit to ring a bell or light a light. And. when the currentstarts to flow along wire 51, this *relay Ha then operates to open thesignal circuitto shut off the light or stop the ringing of the bell;

. In the operation of the back pressure controller valve 23 and of therestricting orifice 20, the pro pane or other gas which flowsthrough'the. small orifice 20 fiows on throughthe valve23 and into thegas main 56. Since the orifice 2D is very small and since the gasreaches the orifice. at only 18 inches of water. column pressure theamount flowing through the orifice 20 and regu lator 23 into the main 56is so small that it has little. to no eifect on .the B. t. u. content ofthe gas in the main. I I l 1 In the illustration given herein I haveshown a three inspirator system with-one standby inspirator, but I donot wish to limit my invention to sucha number of inspirators since itwill be obvious to those skilled in the art that any number ofinspirators of. any desired capacity may be used. For example; ifsixinspirators are of the type of inspirators .47, 48 and 49 then thepressure operated multiple controller. switch .65 should have sixcontrol Wires such as wires 60, 62 and 64 leading to the sixinspirators. In like manner, the number of standby inspirators may bemore than one. For exampleit may be desired to use two or three or moresmaller inspirators in place of the large one which I have described. i1

Materials of constructionmay ordinarilybbe selectedfrom those availableon the market and suitablefor the purpose at hand. In like mariner,

the solenoid control valves, the pressure'operated 7 multiple controllerswitch 65 and the zero governor throttle valve assembly 25, the backpressure regulator 23 and the constant pressure outlet valves 4, H andI8, are all standard equipment and may be purchased from manufacturersor dealers.

It will be obvious to those skilled in the art that many variations andalterations may be made in such a system as herein disclosed and yetremain within the intended spirit and scope of my invention. I wish tobe limited not by the particular example given but only by the appendedclaims.

Having disclosed my invention, I claim:

1. In an electrically operated gas-air mixing system which is operableduring times of electric power failure as well as during times whenelectric power is available, the combination of a source of liquefiedgas under pressure, afirst inspirator for mixing air with gas, a conduitfor passage of gas from said source to said first inspirator, a gasmain, a conduit for passage of mixed air and gas from said firstinspirator to said gas main, a first electrically operated control valvefor controlling the fiow of gas from said source to said firstinspirator, said electrically operated control valve adapted to openwhile electric current flowing to the. electricalecontrol of ;said valveand to'close. whencurrent-is not flowing thereto, a first pressureresponsive control meansadaptedto. control saidfirstelectricallyoperated control valve in response to gas mainpressure, asecond in pirator .for mixing air with; as,,@a-. conduit-forjpassage of;gas from said. source to .said second inspirator, a conduitforrpassageof mixedair and gas-from saidsecond. inspirator to "saidgasmain, a second electrically operated control. valve for controllingthe-gflow cigas. from said. source to said second inspirator,saidsecondelectrically operated control valve adapted. to: close whenelectric current flowing to the :electricalcontrol oi said second valveand to. open when currentv is not flowing thereto; a. second...pressure-responsive control means. adapted: to.:contro1. said secondvelectrically operatedcontrol valvein response torgas mainpressnreandmsaidifirst and second electrically operated control valves.operated by electricity from a commonlsource. 12;; Int an. electricallyoperatedgas-air mixing system. which is'op'erable'during timesjofelectric poweriiailure iaswell' as during times when electric powerxiiavailable, the combination.comprising av source .ofliquefied gas underpressure, a first inspirator means for mixing airwith gas, a gas-main,a' first conduit for passage ofmixedair and gas fromsaidinspirator meansto said main, a firstcOnduitmeansfQr passage of gasfrom said source; tosaid. inspirator means, a pressure reducing means .insaid. conduitmeans, said pressure. reducing means in said conduit means re.-sponsive. to pressure in said gas main, a first om-off. electricallyoperated flow control valve in said. conduit means, said firstelectrically operated flow-control valve adapted to remain open duringsuchtime as electric current is flowing to the. electrical. control ofsaid flow-control valve and to close when current is not flowingthereto, a first "pressure responsive control means adapted to controlsaid first electrically operated control valve in response to gas mainpressure, a second inspirator for mixing air with gas at a greater ratethan said first inspirator means, a second conduitfor passage: ofair-gas mixture from said second inspiratorto said gas main, a secondconu t en e seem s dewe rs reducing. means in. said. first conduit meanssaid second inspirator, asecond electricallyroper ated on-offflow-control valve in said secondzcon v duitmeans said :secondelectrically operated flow-control valve adapted to remain closed duringsuch time as" electric. current is fiow-ingtothe electrical control ofsaid second. flow-control valve and to openwhen. current. is. not.flowing thereto, .a.-second: pressure responsive control means adapted;to controlzsaid. second. electrically operated on -ofi control valve inresponse-to..gas main pressure andsaid firstrand second electriecallyoperatedcontrol valves operated city fromacommonsource,

3. The apparatusof claimz-inwhich said first inspirator means. includesa plurality-of inspirators, said-first 'on.-oif electrically operatedflowcontrol: valveincludes a ,pluralityot onx-off elec? tricallyoperated flowcontrol. valves, one eacl'r of said plurality of on-ofielectrically operatedfiowcontrol valves disposed in said conduitmeanssto control flow ofgas fromsaidsource to one each of said pluralityofinspirators, and saidplurality of on-oif electrically operated :flowcontrolva-lves adapted. to close. and to open successively in re:-sponse to successive changes of :pressure in said gas. main, and eachof. said plurality of: valves adapted to close'in 'caseof electric powerfailure, and wherein said secondelectrically operated on-ofi flowcontrol valve is responsivestoipressure in said gas main and is adaptedto opezrini case electric poweris cutoff therefrom.

4. The apparatus of claim 3' further characterized by an alarm means.disposedi'operatively with said second electricallyioperatedon'vofliinow control. valve to. indicate the opening of this valve. 7

DAVIDW. S'HAEFFER;

REFERENCES CITED The following references are of recordi'inthe file ofthis patent? UNITED STATES PATENTS' Numberv by electrls

1. IN AN ELECTRICALLY OPERATED GAS-AIR MIXING SYSTEM WHICH IS OPERABLEDURING TIMES OF ELECTRIC POWER FAILURE AS WELL AS DURING TIMES WHENELECTRIC POWER IS AVAILABLE, THE COMBINATION OF A SOURCE OF LIQUEFIEDGAS UNDER PRESSURE, A FIRST INSPIRATOR FOR MIXING AIR WITH GAS, ACONDUIT FOR PASSAGE OF GAS FROM SAID SOURCE TO SAID FIRST INSPIRATOR, AGAS MAIN, A CONDUIT FOR PASSAGE OF MIXED AIR AND GAS FROM SAID FIRSTINSPIRATOR TO SAID GAS MAIN, A FIRST ELECTRICALLY OPERATED CONTROL VALVEFOR CONTROLLING THE FLOW OF GAS FROM SAID SOURCE TO SAID FIRSTINSPIRATOR, SAID ELECTRICALLY OPERATED CONTROL VALVE ADAPTED TO OPENWHILE ELECTRIC CURRENT IS FLOWING TO THE ELECTRICAL CONTROL OF SAIDVALVE AND TO CLOSE WHEN CURRENT IS NOT FLOWING THERETO, A FIRST PRESSURERESPONSIVE CONTROL MEANS ADAPTED TO CONTROL SAID FIRST ELECTRICALLYOPERATED CONTROL VALVE IN RESPONSE TO GAS